1. Field of the Invention
The present invention relates to novel 6-fluoro-1,4-dihydro-4-oxo-7-substituted piperazinylquinoline-3-carboxylic acids which have an excellent antibacterial effect, its pharmacologically-acceptable salts, and process for preparing the same.
More particularly, the present invention relates to novel 6-fluoro-1,4-dihydro-4-oxo-7-substituted piperazinylquinoline-3-carboxylic acids represented by the general formula (I), ##STR2## wherein R.sub.1 is a lower alkyl group having 1 to 4 carbon atoms, a vinyl group, a 2-fluoroethyl group, or a 2-hydroxyethyl group; R.sub.2, R.sub.3 and R.sub.4 each is a hydrogen, or a lower alkyl group having each 1 to 4 carbon atoms; R.sub.5 is a lower alkyl group having 1 to 4 carbon atoms and R.sub.6 is a hydrogen, or a fluorine atom, its pharmacologically acceptable salt and process for preparing the same.